29 Dec
2005
29 Dec
'05
3:15 p.m.
Tony Duell wrote:
I believe there have been current loop cards for PCs (the current loop
interface was used industrially, and no I am not thinking of the
_analogue_ current loop used for industrial sensors)). But I've not seen
a combined RS232 and current loop card for a PC other than the original
IBM one.
[1] Note for the uninitiated. The IBM serial card
has 2 odd features that
were not present in most, if not all, clones. The first is that it can
pull pin B8 (IIRS) low during I/O reads, needed if the card is used in
slot 8 of the IBM PC/XT. The second is that it has a current loop
interface as well as RS232 .
Does any of the newer serial cards have the current loop option? Was it only TTY's that used the current loop?
Oh no. A lot of serial terminals did (DECwriters, HP terminals, etc. IIRC
the serial interface for the HP9825 series could do current loop (maybe
the one for the 80 series to). Somewhere I have a couple of control
interfaces that are current loop on the host side. I am alos pretty sure
I've seem a modem with a current loop interface on it. And of course most
minicomputers had current loop interfaces (if only to link to teletypes).
-tony